Research

Supernovae

With collaborators we have been developing the jet feedback mechanism to explain the explosion of massive stars. The morphology of some supernovae show indeed signatures of jets, sometimes similar to planetary nebulae. We take such morphological features to indicate that massive stars are exploded by jets.

On the left isan image from the paper by Ealeal Bear, Aldana Grichener & Noam Soker. This figure compares similar morphological features between the supernovae remnant RCW 103 and three planetary nebulae, A 63 (image taken from Mitchell et al. 2007), NGC 40 (both images are from Meaburn et al. 1996), and NGC 3918 (both images are from Corradi et al. 1999; images are rotated so that the jets are vertical). The image of RCW 103 is a composite X-ray image
in three energy bands (low=red, medium=green, highest=blue) combined with an optical image from the Digitized Sky Survey (image taken from the Chandra website based on Reaet al. 2016). The proposed original directions of the, already dead, jets in the super ova remnant RCW 103 are marked by yellow thick arrows.

ILOTs: Intermediate-Luminosity Optical Transients

With Amit Kashi we classify objects with luminosity between novae and supernovae. We argue that most of them are powered by gravitational energy of stellar merger or accretion in a binary system. For details see here.

Morphology

One of my research topics is to explain the similar morphologies of some of the objects, as seen in the figures below (the colors are not real). The common shaping mechanism is the launching of jets by a compact object at the center. Images are mostly from the Hubble Space Telescope.

Planetary Nebulae: The figures above are images of planetary nebulae — clouds of gas around dying-sun like stars. Typical size is one light year. For more information, credits, and explanation see catalog compiled by Bruce Balick.

The gas around the massive binary system Eta Carinae (left) and around Supernovae 1987A (right) have shapes similar to that of some planetary nebulae. For more on the similarities see my Perspective in Science (2007).

More intriguing is the similarity of some planetary nebulae to X-ray deficient bubbles in clusters of galaxies. On the left is The Owl planetary nebula shown in optical light (Guerrero et al. 2003), and on the right is the Perseus cluster of galaxies taken in X-ray by the Chandra X-ray Observatory. At the center of both objects there is a pair of fainter bubbles. The right image covers a region more than ten thousand times as large as the region covered by the left image. The cloud of gas in the planetary nebula (left) is at about ten thousands degrees Kelvin (or Celsius), while the cluster’s gas (right) is at a temperature of tens of millions of degrees Kelvin. The bubbles are formed by fast jets, one jet per bubble, which inflate the bubbles by filling it with hot tenuous gas.